1

Thomas RoserEICAC meeting

February 28, 2014"

Facility Overview BNLT. Roser for the eRHIC design team"

"   RHIC facility performance""   eRHIC design""   eRHIC R&D""   eRHIC preliminary schedule and

cost estimate"

1

eRHIC Design Study An Electron-Ion Collider at BNL

DRAFT

February 2014

2 2

RHIC"

NSRL"LINAC"Booster"

AGS"

Tandems"

STAR"6:00 o’clock"

PHENIX"8:00 o’clock"

Electron lenses"10:00 o’clock"

Polarized Jet Target"12:00 o’clock"

RF"4:00 o’clock"

(Electron cooling)"2:00 o’clock"

RHIC – a High Luminosity (Polarized) Hadron Collider"

Operated modes (beam energies):"Au – Au "3.8/4.6/5.8/10/14/32/65/100 GeV/n"U – U "96.4 GeV/n"Cu – Cu "11/31/100 GeV/n"p↑ – p↑ "11/31/100/205/250/255 GeV "d – Au* "100 GeV/n "Cu – Au* "100 GeV/n "Planned or possible future modes:"Au – Au "2.5 GeV/n p↑ – A* "100 GeV/n (A = Au, Cu, Al) " "3He – A* "100 GeV/n (A = Au, Cu, Al)"p↑ – 3He↑* "166 GeV/n (*asymmetric rigidity)"

Achieved peak luminosities:"Au – Au (100 GeV/n) "195 × 1030 cm-2 s -1"p↑ – p↑ (255 GeV) "245 × 1030 cm-2 s -1"Other large hadron colliders (scaled to 255 GeV):"Tevatron (p – pbar) "110 × 1030 cm-2 s -1"LHC (p – p) "493 × 1030 cm-2 s -1"

EBIS"

BLIP"

3 3

"   Further upgrades:""   56 MHz srf system to reduce vertex length (commissioning this RHIC run)""   Electron lenses to ~ double pp luminosity (engineering test this RHIC run)""   Facility availability is typically well above 80% (FY12: 85%; FY13: 84%)""   Calendar time-in-store (physics) is about 60% (~100 hours per week)"

RHIC Integrated Luminosity and Polarization (RHIC II performance!)"

Heavy ion runs"

Inte

grat

ed n

ucle

on-p

air l

umin

osity

LN

N [p

b-1 ]"

Polarized proton runs"

Inte

grat

ed lu

min

osity

L [p

b-1 ]"

4 4 eRHIC: QCD Facility at BNLAdd an electron accelerator to the existing $2.5B RHIC

including existing RHIC tunnel and cryo facility"

e-"

p"

Unpolarized and 80% polarized electrons:15.9 GeV"(6.6 – 21.2 GeV)"

Pol. light ions (He-3) 17 - 167 (184*) GeV/u"

Light ions (d, Si, Cu)"Heavy ions (Au, U)"10 - 100 (110*) GeV/u"

70% polarized protons "25 - 250 (275*) GeV"

Center-of-mass energy range: 30 – 145 GeV"Any polarization direction in electron-hadron collisions"

e-"

protons"electrons"

* It is possible to increase RHIC ring energy by 10%""

5 5

eRHIC design""   Up to 21.2 GeV electron beam accelerated with Energy Recovery Linac (ERL) inside

existing RHIC tunnel collides with existing 250 GeV polarized protons and 100 GeV/n HI RHIC beams"

"   Single collision of each electron bunch allows for large disruption, giving high luminosity and full electron polarization transparency"

"   Accelerator R&D for highest luminosity: High current (50 mA) pol. electron gun (Gatling gun); High average current ERL with FFAG passes; Coherent electron cooling of hadron beam"

"   ERL with 1.32 GeV SRF Linac and two FFAG recirculating rings (1.33 – 6.62 GeV; 7.94 – 21.16 GeV) allow for full luminosity (> 1033 cm-2 s-1) up to 15.9 GeV and reduced luminosity up to 21.2 GeV"

"   Nov. 2013 C-AD MAC review: ”The MAC congratulates the eRHIC design team for its ingenious and novel use of the FFAG concept.”"

50 mA polarized electron gun (Gatling gun)"

eRHIC

6 6

Evolution of electrons in ERL with NS-FFAG""   Polarized electron bunch starts in one cathode of Gatling Gun""   Acceleration in SRF CW cavity to 12 MeV and first injection into 1.32 Linac""   After Linac, at 1.33 GeV, spreader brings electron bunch onto correct orbit correct

optics functions for first pass in low energy FFAG ring""   Combiner matches optical functions to Linac and brings orbit to center line""   After second pass through Linac, at 2.65 GeV, a second line of spreader matches to

second turn in low energy FFAG.""   Continue for total of five turns and six passes through Linac (7.94 GeV)""   Spreader now matches electron bunch to first pass through high energy FFAG ring""   Continue for six turns through high energy FFAG and 1.32 GeV Linac, which brings

energy to 15.9 GeV ""   On highest energy pass through high energy FFAG beam is being split off for collision

with hadron beam in detector.""   The collision occurs with a crossing angle of 10 mrad. The electron and hadron bunch

are each rotated by 5 mrad using crab cavities for head-on collisions.""   The electron bunch is then delayed by 180 degrees to enter Linac on decelerating

phase""   After exactly retracing the same path as during acceleration (7 passes through the

high energy FFAG, 5 passes through the low energy FFAG and 12 decelerating passes through the Linac) the electron bunch is getting dumped at 12 MeV. "

7 7

eRHIC beam parameters and luminosities"

"   15% of the hadron beam intensity presently achieved in RHIC: allows to operate with present RHIC vacuum chamber (e.g. no coating is needed) and without space-charge compensation at lower hadron energies."

"   With vacuum chamber coating a 10-fold higher luminosity can be reached. "

8

Luminosity versus beam energy""   Luminosity versus hadron beam

energy""   For 15.9 GeV electron energy or

less""   Limited by hadron beam-beam

parameter above 100 GeV and space charge below 100 GeV"

"   Luminosity versus electron beam energy"

"   Limited by maximum SR power of 12 MW above 15.9 GeV"

0"

0.2"

0.4"

0.6"

0.8"

1"

1.2"

1.4"

0" 50" 100" 150" 200" 250" 300"

Luminosity

,+103

3+cm

02s01

+

Proton+energy,+GeV+

Defined&by&ΔQsp&=&0.035&

Defined&by&&ξp=0.015&

0"

0.2"

0.4"

0.6"

0.8"

1"

1.2"

10" 12" 14" 16" 18" 20" 22"

Luminosity

*redu

c/on

*factor*

Electron*energy,*GeV*

9 9

Electron polarization in eRHIC""   Only longitudinal polarization is needed

in the IPs ""   90% longitudinally polarized e-beam

from DC gun with strained-layer super-lattice GaAs-photocathode with polarization sign reversal by changing helicity of laser photons"

"   Integer number of 180-degrees spin rotations between gun and IPs"

"   Depolarization due to beam energy spread: 6% (11%) for 15.9 GeV (21.2 GeV) with harmonic cavities to compensate the energy spread from the main linac "

"   With the linac energy of 1.32 GeV the polarization is longitudinal at both IPs."

Polarized e-gun

ϕd, γd

ϕ0, γ0

ϕ

stays in horizontal plane"and rotates in arcs around "

vertical direction""

€

v e

€

p e

€

p e

0"

10"

20"

30"

40"

50"

60"

70"

80"

90"

100"

0" 1" 2" 3" 4" 5" 6" 7" 8" 9" 10"

Polariza(

on,+%

+

rms+bunch+length,+mm+

Design"

10 10

FFAG recirculation arcs""   Non-scaling (tune changes) Fixed-

Field Alternating Gradient beam transport (D. Trbojevic)"

"   Very strong focusing channel can transport large energy range"

"   Small quadrupole offsets bend the beams adiabatically if bend radius is much larger than cell length"

"   2 FFAG rings: 1.33 – 6.62 GeV, 7.94 – 21.16 GeV"

"   Permanent magnets possible"

(S. Brooks)

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Beam spreader/combiners on either side of Linac""   Separate/combine the 16 beams with different energies between FFAG

arcs and CW Linac""   Used to match the beam optics of linac and FFAGs and for rough and

fine time of flight adjustments""   Vertical chicane for time-of-flight adjustment not shown"

(N. Tsoupas)

12 12

e-Beam bunch pattern""   ~ 900 ns gap to eliminate ion accumulation""   Every 16 RHIC revolution periods inject one bunch into the gap. Its trajectory on

the trip to 21.2 GeV and back will be measured by single pass BPM.""   Information from these bunches is used to correct the orbit of all passes"

BPM bunches"

13 13

eRHIC high-luminosity IR with β* = 5 cm"

"   10 mrad crossing angle and crab-crossing""   90 degree lattice and beta-beat in adjacent

arcs (ATS) to reach beta* of 5 cm with good dynamic aperture"

"   Combined function triplet with large aperture for forward collision products and with field-free passage for electron beam"

"   Only soft bends of electron beam within 60 m upstream of IP"

14 14

High CW current polarized electron gun""   Matt Poelker (JLab) achieved 4 mA polarized e-beam with good lifetime""   More current with effectively larger cathode area""   Test at MIT with very large cathode area""   Gatling gun: multiple cathodes to effectively increase cathode area""   Gatling Gun Test: twice the current from two cathodes with same lifetime (by end of

2014)"

15 15

Energy Recovery Linac (ERL) Test Facility""   Test of high current (50 mA, 12 passes eRHIC), high brightness ERL operation""   Highly flexible return loop lattice to test high current beam stability issues""   Gun rf tested at 2 MV; beam from gun: April 2014, recirculation: 2015/16""   Gun and cavity will be used for ERL of Low Energy RHIC electron Cooling "

Return loop"

5 Cell SRF “single mode” cavity"Q > 1010 @20 MV/m CW"

0" 20"10"109"

1010"

1011"

Accelerating Voltage [MV/m]"

Q"

2-3 MeV

20 MeV

20 MeV 20 MeV

2-3 MeV

SC RF Gun

SC 5 Cell cavity

Beam dump

1 m"

16

Goal: Prototype eRHIC ERL with Gatling Gun, FFAG permanent magnet arcs, and maybe eRHIC cryo-module. "

NS-FFAG ERL prototype"

50 kW 703.75 MHz system

Cryo-module

SRF cavity e- 220 keV

Laser

e- 220 keV Beam dump

e- 20-80 MeV

Merger system

Return loops 80 MeV

1 m"

17 17

Coherent electron Cooling ""   Idea proposed by Y. Derbenev in 1980, novel scheme

with full evaluation developed by V. Litvinenko""   Fast cooling of high energy hadron beams""   Made possible by high brightness electron beams and

FEL technology""   ~ 20 minutes cooling time for 250 GeV protons → 10x

reduced proton emittance gives high eRHIC luminosity ""   Proof-of-principle demonstration planned with 40 GeV/n

Au beam in RHIC (~ 2015 - 16)"Helical wiggler

prototype "

18 18

eRHIC Cost Estimate""   Bottom-up cost estimation for eRHIC (5 GeV e-beam) has been done

during 2012 (full TPC including ~ 33% average contingency, single IR, not including crab cavities and detector):"

"   Cost optimization for layout with 0.83 GeV SRF CW Linac, 4 local recirculation passes for low energy and 2 re-circulating passes in RHIC tunnel: FY12$ 530M TPC "

""   Present design: 15.9 GeV e-beam at > 1 x 1033 cm-2 s-1 and 21.2 GeV

e-beam with somewhat less luminosity""   1.32 GeV SRF CW Linac, replace 4 small and 2 large recirculation passes with 2

permanent magnet FFAG passes. Scaling from previous above cost:FY12$ 550M TPC"

"   Including second IR ($50M) and crab cavities for 2 IRs ($100M): FY12$ 700M""   Escalated to FY14$: ~750M for TPC (not including detectors)"

"   Plan for new bottom-up cost estimate this year."

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eRHIC Schedule"

Tentative  schedule  for  transition  to  eRHIC

Fiscal  year 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026

12  GeV  Upgrade

FRIB

RHIC  I/II  operations              RHIC  with  LE  cooling

RHIC/eRHIC  ops

Low  energy  coolingePHENIX

sPHENIX  -­‐  ePHENIXeSTAR

eSTAR

eRHIC  machine

Enhanced  eRHIC  detector

R&D/PED/Design  (CD0-­‐CD3)Projects/Construction  (CD3-­‐CD4)Operations/physics

RHIC  with  sPHENIX

sPHENIX

eRHIC

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Readiness of eRHIC""   Technology and performance supporting present eRHIC design:""   250 GeV polarized proton beams with required intensity and brightness""   100 GeV/n Au beams with the required intensity and brightness""   He-3 beams available from new EBIS""   4 mA polarized e beam source demonstrated at Jlab""   10 mA ERL demonstrated (Jlab FEL ERL)""   High energy ERL demonstrated (CEBAF), multi-pass ERL demonstrated (BINP)""   Performance of existing BNL 704 MHz SRF cavity supports eRHIC linac""   Crab cavities tested with beam at KEK""   NS-FFAG principle first demonstrated with EMMA at Daresbury, UK""   Permanent magnets successfully used for Fermilab Recycler"""   Ongoing eRHIC R&D:""   Prototyping of Gatling Gun polarized electron source""   First test with two cathodes this year, prototype supports full tests with 20 cathodes!

"   Strong cooling of hadron beams to ~ 0.2 µm""   Coherent electron Cooling is best concept and needs R&D; CeC PoP in 2015/16 using

40 GeV/n Au beams in RHIC!"   High average current ERL to support operation with high current e-beam""   Results from test-ERL in 2014/15!

"   Prototype eRHIC ERL with Gatling Gun and FFAG arcs""   Proposed to be built using Laboratory PD funds!

"   Development of high gradient crab cavities within LARP (for HL-LHC upgrade)""   Development of polarized He-3 underway in collaboration with MIT""

21 21

Summary"

"   Linac-ring design of eRHIC with new, cost-effective design reaches high luminosity (> 1033 cm-2 s-1) up to 125 GeV CM energy and 145 GeV CM energy for somewhat lower luminosity."

"   Uses existing RHIC facility for HI and polarized proton beam ($2.5B replacement value) and existing RHIC tunnel and cryo-facility for e-beam."

"   R&D under way on high current polarized electron source (Gatling Gun), strong hadron cooling (Coherent electron Cooling) and high current ERL."

""   Very preliminary cost estimate: FY14$ 750M (2 IRs, Crab crossings, no

detectors)"""   Modest upgrades to the hadron ring would support highest luminosity (1034

cm-2 s-1)."

22 22

Back-up slides"

23 23

Recent Reviews""   C-AD Machine Advisory Committee review of eRHIC design (11/2013)""   J. Jowett (CERN), SY Lee (Indiana), G. Neil (TJNAF), K. Saito (MSU), V. Shiltsev

(FNAL), P. Spiller (GSI), R. Talman (Cornell), F. Zimmermann (CERN, Chair)""   CeC Proof-of-Principle review (12/2012)""   O. Brüning (CERN), H. Padamsee (Cornell), R. Palmer (BNL),

V. Lebedev (FNAL, Chair) ""   C-AD Machine Advisory Committee review of test-ERL (10/2012)""   J. Jowett (CERN), G. Krafft (TJNAF), SY Lee (Indiana) K. Ohmi (KEK), V. Shiltsev

(FNAL), P. Spiller (GSI), R. Talman (Cornell), F. Zimmermann (CERN, Chair)""   Gatling Gun Advisory Committee review (6/2012)""   K. Aulenbacher (Mainz, Chair), A. Brachtmann (SLAC), H.-C. Hseuh (BNL),

M. Poelker (TJNAF) ""   DOE ONP C-AD Accelerator R&D review (12/2011)""   A. Chao (SLAC), P. Ostrumov (ANL), K. Robinson (LBNL), C. Sinclair (Cornell), J.

Delayen (ODU), J. Galayda (SLAC)""   eRHIC design review (8/2011)""   J. Delayen (ODU), G. Ganetis (BNL), H.-C. Hseuh (BNL),V. Lebedev (FNAL), M.

Poelker (TJNAF), E. Pozdeyev (MSU/NSCL), P. Wanderer (BNL), F. Zimmermann (CERN, chair)"

"   Cost review of medium energy eRHIC design [internal] (10/2009)""   S. Aronson (Chair), G. Ganetis, M. Harrison, S. Krinsky, M. Marx, P. Pile, M.

Schaeffer, S. Vigdor, F. Willeke"

24 24

Polarized He-3 in RHIC""   Polarized He-3 from new EBIS; test with unpolarized He-3 started""   Polarimetry:""   Relative: He3-C CNI polarimeter; ""   Absolute: He3-He3 CNI polarimeter using polarized He-3 jet"

"   Depolarizing resonances are stronger. However, no depolarization expected with six snakes in RHIC"

STAR"PHENIX"

AGS"LINAC"

BOOSTER"

Pol. H- Source"

Spin Rotators"(longitudinal polarization)"

Siberian Snakes"

He3-C Polarimeter"

Abs. Pol. (He3↑ jet)"

He3-C Polarimeter"

20-50% Helical Partial Siberian Snake"

15 % Helical Partial "Siberian Snake"

Spin Rotators (long. pol.)"

Spin flipper"

Siberian Snakes"

Pol. He-3 Source (EBIS)"

25 25

Simple picture of FFAG""   An ideal eRHIC FFAG cell is comprised of two quadrupoles (F & D) whose

magnetic axes are shifted horizontally with respect to each other by Δ ""   The structure has a natural bilateral symmetry, e.g. all extrema (min and max) are

in the centers of the quadrupoles (independently of any approximation!)!"   Orbit dependence on the energy can be easily found in paraxial approximation""   Everything can be done accurately and analytically – no doubt that

proposed FFAG lattice would work! " zf

Δ

z d

2d!lf! ld!

d! d!

x f = −axdθ + cxd Δ+ dθ( )

axf cxd + axdcxf + 2dcxdcxf

xd = −axfθ − cxf Δ− dθ( )

axf cxd + axdcxf + 2dcxdcxf

axf = cosϕ f ; bxf =sinϕ f

ω f

;cxf = −ω f sinϕ f

axd = coshϕd; bxd =sinhϕd

ωd

;cxd =ωd sinhϕd

ayf = coshϕ f ; byf =sinhϕ f

ω f

;cyf =ω f sinhϕ f

ayd = cosϕd; byd =sinϕd

ωd

;cyd = −ωd sinhϕd

ωd = −eGd

pc;ω f =

eGf

pc. ϕ f ,d =ω f ,dl f ,d

F"

F"F"

D"D"

θ θ

L=2(lF+lD+2d)

Orbit "